Field of the Invention
The invention relates to a coating system for coating print carriers, the coating system having at least one pump, at least one selection valve, a first metering device and a second metering device. The invention also relates to a coating machine having the coating system.
Such coating systems serve, for example, for coating print carriers with zinc white primers, metallic printing inks or clear varnish coats.
German Utility Model DE 296 16 686 U1 illustrates a coating system (note FIG. 4 therein) corresponding to the general type mentioned in the introduction hereto wherein, according to the description that is given, depending upon the printing order, one of the metering devices can be exchanged. The aforementioned utility model illustrates a further coating system (note FIG. 1 therein) which includes only a single metering device and therefore does not actually correspond to the general type of coating systems mentioned in the introduction hereto. This metering device may be constructed in accordance with the anilox metering principle, the scoop-roller metering principle or the nip-roller metering principle.
The specialized journal xe2x80x9cDeutscher Druckerxe2x80x9d [German Printer], number 34 of Sep. 13, 2001, page 26, describes a new product line of the company Harris and Bruno Europe GmbH for fully automatic in-line cleaning, wherein, according to the description given, it is not necessary to change hose systems or pumps, and a chambered doctor blade can remain in position.
Furthermore, the German Utility Model DE 299 13 778 U1 describes a coating system which includes a metering device and a circulation line system. The metering device includes a screen or engraved roller and is therefore constructed in accordance with the anilox metering principle. The circulation line system is made up of a supply line, a return line and pumps. The supply line and the return line are couplable with the metering device. In this last-mentioned utility model, it is noted as advantageous that the circulation line system manages without switching valves and would consequently be uncomplicated.
It is accordingly an object of the invention to provide a coating system for coating print carriers and a coating machine having the system, which overcome the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a coating system for coating print carriers. The system comprises at least one pump, at least one selection valve, a first metering device and a second metering device. The first metering device and the second metering device are constructed differently from one another with respect to metering principles thereof. The at least one pump and the at least one selection valve are assembled or combined into a modular supply unit constructed so as to be compatible both with the first and with the second metering device.
In accordance with another feature of the invention, the first metering device includes, in accordance with the pan-roller metering principle, a storage trough and a dip or pan roller.
In accordance with a further feature of the invention, the second metering device includes, in accordance with the anilox metering principle, a doctor blade and a screen roller.
In accordance with an added feature of the invention, the coating system further includes connecting lines for connecting the supply unit to the first metering device.
In accordance with an additional feature of the invention, the first metering device and the second metering device have respective connections. One of the connecting lines is connected to the connection of the first metering device and is constructed for fitting together with the connection of the second metering device and is thereby connectable to the connection of the second metering device.
In accordance with yet another feature of the invention, the connecting lines are coupled via couplings with further connecting lines which are connected to the supply unit.
In accordance with yet a further feature of the invention, the coating system further includes a coating machine provided with the first metering device. The coating machine has a machine frame or stand, and the couplings are disposed locally fixed on the machine stand.
In accordance with yet an added feature of the invention, the supply unit has a frame or stand whereto the pump and a selection valve are fastened.
In accordance with yet an additional feature of the invention, the frame or stand is a closed housing within which the pump and the selection valve are disposed.
In accordance with still another feature of the invention, the coating system further includes a coating-liquid reservoir assigned to the supply unit. The reservoir is disposed outside the housing.
With the objects of the invention in view, there is also provided a coating machine, comprising a coating system for coating print carriers. The system includes at least one pump, at least one selection valve, a first metering device and a second metering device. The first metering device and the second metering device are constructed differently from one another with respect to metering principles thereof. The at least one pump and the at least one selection valve are assembled into a modular supply unit constructed so as to be compatible both with the first and with the second metering device.
In accordance with a further feature of the invention, the coating machine is a printing machine.
In accordance with a concomitant feature of the invention, the coating machine is a varnishing machine.
Thus, the coating system according to the invention has a first metering device and a second metering device which are constructed differently from one another in terms of metering principles thereof. The pump and the selection valve are assembled or combined for forming a modular supply unit or assembly. The supply unit is constructed so as to be compatible both with the first and with the second metering device.
One advantage resulting from the difference between the metering devices is that different coating liquids can be printed by the coating system. For example, a high-viscosity coating liquid can be metered and printed with the aid of the first metering device, and a low-viscosity coating liquid can be metered and printed with the aid of the second metering device.
Advantages resulting from the pump being assembled or combined with the selection valve into a structural unit in the form of the supply unit or assembly are the compact form of construction and therefore the low space requirement of this supply unit. The supply unit may be integrated, for example, into a cabinet or shelf next to a printing or varnishing machine including the metering devices.
An advantage which is to be particularly emphasized is that the supply unit is constructed so as to be selectively couplable with the first and with the second metering device. To execute a printing order, the supply unit, in the state wherein it is coupled to the first metering device, can be operated together with the latter, while the second metering device is not required for executing the printing order and is uncoupled or decoupled from the supply unit. To execute another printing order for which the second metering device is required, but not the first metering device, the second metering device can be coupled, instead of the first metering device, to the supply unit, so that the supply unit and the second metering device can be operated jointly.
The coating system according to the invention may be associated with only a single coating machine, for example a printing machine. For example, the metering devices may be constructed as interchangeable devices which can be inserted selectively, in exchange for one another, into a varnishing unit of the printing machine. In this case, the metering device inserted, respectively, into the varnishing unit is connected to the supply unit which is assigned to the varnishing unit. During the operation of the metering device inserted into the varnishing unit, together with the supply unit, the other metering device may be intermediately stored, maintained or operated within another varnishing unit of the printing machine, the other varnishing unit likewise having a supply unit assigned thereto.
The coating system according to the invention may, however, also be associated jointly with a plurality of coating machines, for example a first printing machine and a second printing machine. For example, the first metering device may be an integral part of a varnishing unit of the first printing machine, and the second metering device an integral part of a varnishing unit of the second printing machine. In this case, the advantages of the coating system according to the invention are brought to bear in a particular way when the supply unit is assigned to the varnishing unit of the first printing machine, such a supply unit is assigned to the varnishing unit of the second printing machine, and the metering devices are constructed as interchangeable devices exchangeable in relation to one another, i.e., the first metering device may also be inserted into the second printing machine, and the second metering device also into the first printing machine.
Further features of the coating system according to the invention and the advantages thereof are described hereinbelow.
In a development or feature which is advantageous in terms of printing of a comparatively high-viscosity coating liquid, the first metering device is constructed in accordance with the scoop-roller metering principle. Consequently, the first metering device includes a storage trough, wherein the coating liquid is intermediately stored, and a dip roller which is disposed in the storage trough and which scoops the coating liquid out of the storage trough.
In a development which is advantageous in terms of printing of a comparatively low-viscosity coating liquid, the second metering device is constructed in accordance with the anilox metering principle. Consequently, the second metering device includes a screen or engraved roller and a doctor blade which bears against the screen or engraved roller. The term xe2x80x9canilox rollerxe2x80x9d, according to which the metering principle of the second metering device is named, is also often used for the terms screen or engraved roller. The screen or engraved roller may have a well or cell screen or be a hatched roller provided with a line screen. The doctor blade may be a two-blade (working blade, closing blade) chambered doctor blade. Depending upon the construction of the chambered doctor blade, the coating liquid can be maintained, within a chamber of the chambered doctor blade, either only under a static pressure (passive pressure) or both under static pressure and under a dynamic pressure (active pressure).
There may, of course, also be provision for constructing either the first metering device or the second metering device in accordance with the nip-roller metering principle. It is likewise possible, in addition to the first metering device constructed in accordance with the scoop-roller metering principle, and to the second metering device constructed in accordance with the anilox metering principle, also to provide a third metering device which is associated with the coating system and which is constructed in accordance with the nip-roller metering principle and likewise so as to be compatible with the supply unit or assembly. It is specific to the nip-roller metering principle that the correspondingly constructed metering device includes two rollers together forming a roller nip, and the roller nip has an upwardly open wedge, into which the coating liquid is fed by a supply line, and wherein a small supply of coating liquid is intermediately stored.
In a development which is advantageous in terms of the formation of a liquid circuit, the supply unit is connected to the first metering device via a plurality of connecting lines, i.e., hollow liquid lines (tubes or hoses).
In a development which is advantageous in terms of decoupling the supply unit from the first metering device and coupling the supply unit to the second metering device, at least one of the connecting lines is connected to a connection of the first metering device and is constructed so as to be connectable to a connection of the second metering device. The connecting line is thus constructed so as to be compatible both with the connection of the first metering device and with the connection of the second metering device and, after being released from the connection of the first metering device, can be connected to the connection of the second metering device. The connecting line compatible with the connections of the metering devices can be attached with the end thereof opposite the connections to the supply unit. According to the development described here, the attachment of the connection line to the supply unit may be of a permanent nature, and it is not necessary to release the connecting line from the supply unit in order to decouple the supply unit from the first metering device and couple it to the second metering device. In terms of the maintenance of the coating system, however, it is advantageous if the connecting line is not attached permanently to the supply unit, but rather releasably. A connection, disposed on the supply unit, for the connecting line may serve for the releasable attachment of the connecting line to the supply unit. The connecting line compatible with the connections of the metering devices may be attached with the end thereof opposite the connections not to the supply unit, but, instead, to a coupling which couples the connecting line to a further connecting line, of which the end opposite the coupling is attached to the supply unit. The coupling may be disposed locally fixed on a machine stand of a coating machine containing the first metering device.
In a development which is likewise advantageous in terms of decoupling or uncoupling the supply unit from the first metering device and coupling the supply unit to the second metering device, the at least two or more connecting lines are attached to the first metering device and are coupled via a corresponding number of couplings to a corresponding number of further connecting lines which are connected to the supply unit. Thus, according to the development described here, there are connecting lines, each of which is attached with one end to the supply unit and with the other end thereof to one of the couplings, respectively. Moreover, according to the development described here, there are connecting lines, each of which is attached with one end to the first metering device and with the other end thereof to one of the couplings, respectively. The couplings may be readily releasable quick-action couplings and may be disposed on a machine stand, preferably a machine side wall, of a coating machine containing the first metering device, locally fixed and close to one another, i.e., in the manner of a multiple plug socket installed on a wall.
In another development which is advantageous in terms of decoupling or uncoupling the supply unit from the first metering device and coupling the supply unit to the second metering device, a first connecting line, via which the supply unit is connected to the first metering device, is connected to a connection of the supply unit, and a second connecting line attached to the second metering device is constructed to fit together with the connection of the supply unit and thus be connectable to the connection. The connection of the supply unit is thus constructed so as to be compatible both with the first connecting line used for the first metering device and with the second connecting line used for the second metering device. In order to uncouple the supply unit from the first metering device and couple it to the second metering device, the second connecting line is connected, instead of the first connecting line, to the connection disposed on the supply unit. Those ends of the connecting lines which are opposite the connection of the supply unit may be attached to the metering devices permanently or in a readily releasable manner. In terms of the maintenance of the coating system, it is advantageous if the first connecting line is attached to the first metering device in a readily releasable manner via a connection disposed on the first metering device, and the second connecting line is attached to the second metering device in a readily releasable manner via a connection disposed on the second metering device.
In the case of a hoselike construction of the connecting line connectable to the respective connection, each of the abovementioned connections of the metering devices and of the supply unit may be in the form of a tubular nipple, onto which the connecting line is slipped and secured by a hose clip. Instead of the hose-coupling type formed of the tubular nipple and hose clip, other types of hose couplings are also suitable for forming each of the connections mentioned. For example, the connecting lines may be connected to the metering devices and to the supply unit via adapters.
In a development which is advantageous in terms of the stability of the supply unit, the latter includes a stand which carries the pump and the selection valve. In addition to the pump already mentioned and to the selection valve already mentioned, a further pump and/or at least one further selection valve (preferably a plurality of further selection valves) and/or an electrical control device may be fastened to the stand. The stand may be in the form of a shelf unit composed of plates or be in the form of a frame composed of battens or tubes.
In a development which is advantageous in terms of the protection of the pump (or pumps), of the selection valve (or selection valves) and, if appropriate, of the electrical control device against dirt, the stand is in the form of a closed housing, within which are disposed the pump (or pumps), the selection valve (or selection valves) and, if present, the control device. The at least approximately box-shaped housing is preferably closed on all sides. In specific instances, instead of the housing being closed all-around, a housing open to one side is also acceptable, for example when the open side of the housing is covered by an adjacent wall, for example a machine side wall or a building wall. Preferably, the housing is in the form of a cabinet provided with at least one door. The dirt against which the parts of the supply unit are to be protected by being disposed within the housing is primarily fluff originating from the print carriers and, where appropriate, powder with which the print carriers, if these are print carrier sheets, are dusted in the sheet delivery of the coating machine. By having the sensitive parts of the supply unit be encased by the housing, it is possible, without regard to the dirt source, namely the coating machine, to place the supply unit as near to the latter as is desired. It is consequently possible to keep the length of the connecting lines very short, thus resulting, in turn, in advantages (reduced consumption of cleaning agents) in the case of an automated self-cleaning of the coating system.
In a development which is advantageous in terms of changing the coating liquid printed by the coating system, a coating-liquid reservoir containing the coating liquid is disposed outside the housing of the supply unit. Thus, instead of the coating-liquid reservoir, another coating-liquid reservoir filled with another coating liquid can be coupled with the supply unit without major outlay, if it is necessary to change the coating liquid from one printing order to another.
The advantages of the coating system according to the invention become clear not only to the user thereof, but also to the manufacturer of the coating system. The latter no longer needs to manufacture another special supply device for each of the metering devices and, instead, can deliver one and the same modular supply unit together with each of the various metering devices.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a coating system for coating print carriers and a coating machine having the system, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.